I. Field of the Invention
The present invention relates generally to tampon applicators. More particularly, the present invention relates to a plastic-type tampon applicator that is biodegradable. The present invention further relates to a plastic-type tampon applicator that remains stable prior to and throughout use. By the unique treatment provided herein, all plastic-type applicators has prolonged flexibility and stable aging. In addition, the present invention includes an outer coating that retains moisture in the applicator and prevents undesirable stickiness.
Typically, tampon applicators, after use, are disposed in toilets, trash receptacles and the like. To prevent unwanted problems in septic systems and waste disposal facilities, tampon applicators must be biodegradable.
Generally, tampon applicators are made from a paper-based or plastic-based material. Certain users prefer plastic-type applicators. Such plastic-type tampon applicators are made typically of a polyethylene that is injection molded or extruded. However, polyethylene is not biodegradable. Other tampon applicators have been made of polyvinyl alcohol, which is water dispersible and biodegradable, however such applicators have been found to be sticky and not stable for long periods of time.
II. Description of the Prior Art
Tampon applicators made from polyvinyl alcohol are shown in U.S. Pat. No. 3,717,149 to Morane, which issued on Feb. 20, 1973; U.S. Pat. No. 3,724,462 to D. E. Hanke, which issued on Apr. 3, 1973; U.S. Pat. No. 3,882,196 to D. E. Hanke, which issued on May 6, 1975; and U.S. Pat. No. 3,911,917 to D. E. Hanke, which issued Oct. 14, 1975. Typically, polyvinyl alcohol is made from higher molecular weight polymers and plasticized with glycerine. Such polyvinyl alcohol, however, has been found to have poor solubility in cold water. The other type of polyvinyl alcohol, known as cold water soluble, is made from internally plasticized and lower molecular weight resins.
A polyvinyl alcohol tampon applicator that claims to be biodegradable and water dispersible is described in U.S. Pat. No. 5,002,526 to L. E. Herring, which issued on Mar. 26, 1991. The tampon applicator is made from a polyvinyl alcohol having less than about 5 percent by weight of plasticizer. This patent states that the use of plasticizers at about 20 percent by weight can be expected to result in increased moisture sensitivity, decreased tensile strength, and migration of the plasticizer from the finished product. Accordingly, this applicator produces a slimy or slippery outer surface, even before contact with water.
Other tampon applicators are made of polyvinyl alcohol with various additives, such as plasticizers and antioxidants. For example, U.S. Pat. No. 4,849,256 to G. F. Newman, which issued on Jul. 18, 1989, provides a method for producing a resin blend including a polyvinyl alcohol (PVA) resin granules that are coated with a plasticizer and then mixed with a powder coating. Other components, such as antioxidants, dyes, and antiblocking agents, may also be incorporated into the finished product. Also, U.S. Pat. No. 5,380,529 to J. Heusser, et al., which issued on Jan. 10, 1995, provides a pharmaceutical preparation for application to a vagina having a polyvinyl alcohol and at least two additional components. One component is selected from the group consisting of wetting agents, non-ionic surface active agents and dispersing agents.
Other examples of compositions that include polyvinyl alcohols with various additives are described in U.S. Pat. No. 5,190,712 to T. Oishi, et al., which issued on Mar. 2, 1993; U.S. Pat. No. 4,140,668 to Sumi, et al., which issued in 1979; U.S. Pat. No. 4,309,510 to R. Kleber, which issued on Jan. 5, 1982; U.S. Pat. No. 4,323,492 to W. Zimmermann, et al., which issued on Apr. 6, 1982; U.S. Pat. No. 4,389,506 to T. Hassall, Jr., which issued on Jun. 21, 1983; U.S. Pat. No. 4,454,194 to R. H. Luebbe, Jr., which issued on Jun. 12, 1984; U.S. Pat. No. 4,469,837 to P. Cattaneo, which issued on Sep. 4, 1984; U.S. Pat. No. 4,478,971 to L. Ballard, which issued on Oct. 23, 1984; U.S. Pat. No. 4,479,997 to Masterson, et al., which issued in 1984; U.S. Pat. No. 4,482,599 to Luebbe, Jr., et al., which issued in 1984; U.S. Pat. No. 4,488,158 to Wirnowski, which issued in 1984; U.S. Pat. No. 4,536,532 to G. W. Miller, et al, which issued on Aug. 20, 1985; U.S. Pat. No. 4,542,178 to W. Zimmermann, et al., which issued on Sep. 17, 1985; U.S. Pat. No. 4,547,329 to J. R. Dombroski, et al., which issued on Oct. 15, 1985; U.S. Pat. No. 4,611,019 to H. H. Lutzmann, et al., which issued on Sep. 9, 1986; U.S. Pat. No. 4,656,216 to A. Muller, et al., which issued on Apr. 7, 1987; U.S. Pat. No. 4,692,494 to G. G. Sonenstein, which issued on Sep. 8, 1987; U.S. Pat. No. 4,849,256 to G. F. Newman, et al., which issued on Jul. 18, 1989; U.S. Pat. No. 4,950,513 to V. K. Mehra, which issued on Aug. 21, 1990; U.S. Pat. No. 5,028,648; U.S. Pat. No. 5,070,126 to S. Toyonishi, et al., which issued on Dec. 3, 1991; U.S. Pat. No. 5,093,401 to U. Claussen, et al., which issued on Mar. 3, 1992; U.S. Pat. No. 5,137,969 to F. L. Marten, et al., which issued on Aug. 11, 1992; U.S. Pat. No. 5,187,226 to M. Kamachi, et al., which issued on Feb. 16, 1993; U.S. Pat. No. 5,190,712 to T. Oishi, et al., which issued on Mar. 2, 1993; U.S. Pat. No. 5,258,430 to C. Bastioli, et al., which issued on Nov. 2, 1993; U.S. Pat. No. 5,262,458 to C. Bastioli, et al., which issued on Nov. 16, 1993; U.S. Pat. No. 5,349,000 to Robeson, et al., which issued in 1994; U.S. Pat. No. 5,360,830 to C. Bastioli, et al., which issued on Nov. 1, 1994; and U.S. Pat. No. 5,380,529 to J. Heusser, et al., which issued on Jan. 10, 1995.
For use, the outer surface of a plastic-based tampon applicator should not be sticky, slippery or slimy. The outer surface of a tampon applicator has been coated with a water-insoluble polymer in an attempt to prevent such stickiness or slipperiness. For example, U.S. Pat. No. 4,372,311 to J. E. Potts, which issued on Feb. 8, 1983, provides a disposable article made from a water-soluble polymer in which the surface of the article is coated with a degradable water-insoluble polymer. The patent states that the degradable water-insoluble polymer can be a cyclic ester polymer, a poly (.beta.-hydroxy butyrate), dialkanoyl polymers, such as polyesters and polyurethanes derived from aliphatic polyols, and ethylene polymers.
Thus, there still is a need for a plastic-type tampon applicator that is sufficiently moisture resistant to provide a dry, outer surface before and during use and, yet, water-dispersible for disposal into a toilet bowl after use. Moreover, there is still a need for such a plastic-based tampon applicator that remains flexible and stable for a long period of time.